Insulation has been used to insulate a wide of variety of locations where thermal insulation or sound attenuation is desired or required. Insulation has been used, for example, in vehicles, in walls, floors, ceilings and attics of building, in and around appliances and the like. Available insulation materials have several drawbacks, including moisture uptake, the fibers of fibrous insulation material may become airborne during handling and installation, and the insulation material may become embedded in the installer's skin, causing irritation and possibly infection.
To solve the problems of moisture uptake and fibrous insulation becoming airborne during handling and installation, the insulation material has been encased in film materials. (See, for example, U.S. Pat. No. 5,362,539 to Hall et al. and U.S. Pat. No. 5,624,726 to Sanocki et al.). Films have drawbacks as an insulation encasement material including the film traps air around the insulation material creating a “pillow” or “balloon” effect, making it difficult to transport the encased insulation material and to manipulate the insulation material during installation so that it can fill a cavity to be filled. To overcome this problem, vents are inserted into the film to allow trapped air to escape from the encasement. However, these vents may allow for the insulation material to escape from the encasement and may allow water to enter inside the encasement and wet the insulation material, thereby defeating one of the purposes for encasing the insulation material.
In addition, film materials do not provide sound attenuation properties over a wide range of frequencies, since the film is non-porous. In applications where sound insulation is needed or desired, the films are not a very effective in attenuating sound. Therefore, there is a need in the art for a sound insulation material which is encased to avoid the problems associated with unencased insulation materials, while the encasement material provides improved sound insulation properties.